1. Field of the Invention
The present invention relates to pipelines and, in particular, to methods and apparatus used in longitudinally extending pressurized headers or other pipelines.
2. Description of the Prior Art
In the course of plant expansion programs, it is often necessary to extend pressurized headers or other pipes from points where they are terminally sealed with a closure plate. Heretofore, two principal methods of effecting such an extension operation were known. The first of these methods involved shutting down the line and bleeding gaseous contents into the atmosphere. For many applications, however, such a procedure may be unsuitable because it may involve the release of an undue amount of pollutants in the area surrounding the pipeline. Furthermore, a shutdown of a header, even for a relatively short period of time, may involve the interruption of service to critical processes so as to be economically detrimental. An alternate method of extending a header is to pressure tap the line and convey its contained fluid in a specially constructed bypass line. While allowing the pressured header to be extended without the necessity of a shutdown, the construction of a bypass can be expensive and time consuming. It is, therefore, the object of the present invention to provide a means for extending a header which avoids the above described difficulties.